Since organic electroluminescence devices are capable of obtaining a light emission with high luminance intensity by low-voltage driving, the devices have been actively researched and developed. In general, organic electroluminescence devices have an organic layer including a light emitting layer and a pair of electrodes with the organic layer interposed therebetween, and utilize, for light emission, energy of the exciton generated as a result of recombination of electrons injected from a cathode and holes injected from an anode in the light emitting layer.
Improvement in the efficiency of devices has been recently made by using a phosphorescence emitting material. As a phosphorescence emitting material, iridium complexes, platinum complexes and the like are known (see, for example, Patent Document 1).
In addition, doped devices using a light emitting layer including a host material doped with a light emitting material have been utilized widely. Development of host materials has been conducted actively and an invention using an aromatic polycyclic condensed ring-based material as a host material has been known (see Patent Document 2, for example). Further, with regard to a phosphorescent material, an invention related to a light emitting spectrum with high color purity obtained by introducing a substituent to a specific position has been known (see Patent Document 3).
Devices have insufficient external quantum efficiency and durability, and require further improvement in their characteristics. Moreover, an increment in driving voltage caused by temperature of usage environment becomes an additional problematic obstacle in practice, and an improvement in such a problem is needed.
Patent Document 2 discloses use of a chrysene derivative as a host material for the purpose of fabrication of a device with high efficiency and long service life. In addition, Patent Document 3 discloses use of Ir complexes of phenylquinoline-based ligands having a substituent at a specific position in a high-performance red phosphorescence device. Further, Patent Document 4 discloses an embodiment in which a chrysene derivative is used as a host material for Ir complexes of specific phenylquinoline-based ligands, but no studies have been conducted about a difference in driving voltage increment upon driving under different driving environments, and thus, such an embodiment is highly problematic in practice.